drivers/cpufreq/elanfreq.c

   1 /*
   2  *      elanfreq:       cpufreq driver for the AMD ELAN family
   3  *
   4  *      (c) Copyright 2002 Robert Schwebel <r.schwebel@pengutronix.de>
   5  *
   6  *      Parts of this code are (c) Sven Geggus <sven@geggus.net>
   7  *
   8  *      All Rights Reserved.
   9  *
  10  *      This program is free software; you can redistribute it and/or
  11  *      modify it under the terms of the GNU General Public License
  12  *      as published by the Free Software Foundation; either version
  13  *      2 of the License, or (at your option) any later version.
  14  *
  15  *      2002-02-13: - initial revision for 2.4.18-pre9 by Robert Schwebel
  16  *
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/init.h>
  22
  23 #include <linux/delay.h>
  24 #include <linux/cpufreq.h>
  25
  26 #include <asm/cpu_device_id.h>
  27 #include <asm/msr.h>
  28 #include <linux/timex.h>
  29 #include <linux/io.h>
  30
  31 #define REG_CSCIR 0x22          /* Chip Setup and Control Index Register    */
  32 #define REG_CSCDR 0x23          /* Chip Setup and Control Data  Register    */
  33
  34 /* Module parameter */
  35 static int max_freq;
  36
  37 struct s_elan_multiplier {
  38         int clock;              /* frequency in kHz                         */
  39         int val40h;             /* PMU Force Mode register                  */
  40         int val80h;             /* CPU Clock Speed Register                 */
  41 };
  42
  43 /*
  44  * It is important that the frequencies
  45  * are listed in ascending order here!
  46  */
  47 static struct s_elan_multiplier elan_multiplier[] = {
  48         {1000,  0x02,   0x18},
  49         {2000,  0x02,   0x10},
  50         {4000,  0x02,   0x08},
  51         {8000,  0x00,   0x00},
  52         {16000, 0x00,   0x02},
  53         {33000, 0x00,   0x04},
  54         {66000, 0x01,   0x04},
  55         {99000, 0x01,   0x05}
  56 };
  57
  58 static struct cpufreq_frequency_table elanfreq_table[] = {
  59         {0,     1000},
  60         {1,     2000},
  61         {2,     4000},
  62         {3,     8000},
  63         {4,     16000},
  64         {5,     33000},
  65         {6,     66000},
  66         {7,     99000},
  67         {0,     CPUFREQ_TABLE_END},
  68 };
  69
  70
  71 /**
  72  *      elanfreq_get_cpu_frequency: determine current cpu speed
  73  *
  74  *      Finds out at which frequency the CPU of the Elan SOC runs
  75  *      at the moment. Frequencies from 1 to 33 MHz are generated
  76  *      the normal way, 66 and 99 MHz are called "Hyperspeed Mode"
  77  *      and have the rest of the chip running with 33 MHz.
  78  */
  79
  80 static unsigned int elanfreq_get_cpu_frequency(unsigned int cpu)
  81 {
  82         u8 clockspeed_reg;    /* Clock Speed Register */
  83
  84         local_irq_disable();
  85         outb_p(0x80, REG_CSCIR);
  86         clockspeed_reg = inb_p(REG_CSCDR);
  87         local_irq_enable();
  88
  89         if ((clockspeed_reg & 0xE0) == 0xE0)
  90                 return 0;
  91
  92         /* Are we in CPU clock multiplied mode (66/99 MHz)? */
  93         if ((clockspeed_reg & 0xE0) == 0xC0) {
  94                 if ((clockspeed_reg & 0x01) == 0)
  95                         return 66000;
  96                 else
  97                         return 99000;
  98         }
  99
 100         /* 33 MHz is not 32 MHz... */
 101         if ((clockspeed_reg & 0xE0) == 0xA0)
 102                 return 33000;
 103
 104         return (1<<((clockspeed_reg & 0xE0) >> 5)) * 1000;
 105 }
 106
 107
 108 /**
 109  *      elanfreq_set_cpu_frequency: Change the CPU core frequency
 110  *      @cpu: cpu number
 111  *      @freq: frequency in kHz
 112  *
 113  *      This function takes a frequency value and changes the CPU frequency
 114  *      according to this. Note that the frequency has to be checked by
 115  *      elanfreq_validatespeed() for correctness!
 116  *
 117  *      There is no return value.
 118  */
 119
 120 static void elanfreq_set_cpu_state(struct cpufreq_policy *policy,
 121                 unsigned int state)
 122 {
 123         struct cpufreq_freqs    freqs;
 124
 125         freqs.old = elanfreq_get_cpu_frequency(0);
 126         freqs.new = elan_multiplier[state].clock;
 127
 128         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 129
 130         printk(KERN_INFO "elanfreq: attempting to set frequency to %i kHz\n",
 131                         elan_multiplier[state].clock);
 132
 133
 134         /*
 135          * Access to the Elan's internal registers is indexed via
 136          * 0x22: Chip Setup & Control Register Index Register (CSCI)
 137          * 0x23: Chip Setup & Control Register Data  Register (CSCD)
 138          *
 139          */
 140
 141         /*
 142          * 0x40 is the Power Management Unit's Force Mode Register.
 143          * Bit 6 enables Hyperspeed Mode (66/100 MHz core frequency)
 144          */
 145
 146         local_irq_disable();
 147         outb_p(0x40, REG_CSCIR);                /* Disable hyperspeed mode */
 148         outb_p(0x00, REG_CSCDR);
 149         local_irq_enable();             /* wait till internal pipelines and */
 150         udelay(1000);                   /* buffers have cleaned up          */
 151
 152         local_irq_disable();
 153
 154         /* now, set the CPU clock speed register (0x80) */
 155         outb_p(0x80, REG_CSCIR);
 156         outb_p(elan_multiplier[state].val80h, REG_CSCDR);
 157
 158         /* now, the hyperspeed bit in PMU Force Mode Register (0x40) */
 159         outb_p(0x40, REG_CSCIR);
 160         outb_p(elan_multiplier[state].val40h, REG_CSCDR);
 161         udelay(10000);
 162         local_irq_enable();
 163
 164         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 165 };
 166
 167
 168 /**
 169  *      elanfreq_validatespeed: test if frequency range is valid
 170  *      @policy: the policy to validate
 171  *
 172  *      This function checks if a given frequency range in kHz is valid
 173  *      for the hardware supported by the driver.
 174  */
 175
 176 static int elanfreq_verify(struct cpufreq_policy *policy)
 177 {
 178         return cpufreq_frequency_table_verify(policy, &elanfreq_table[0]);
 179 }
 180
 181 static int elanfreq_target(struct cpufreq_policy *policy,
 182                             unsigned int target_freq,
 183                             unsigned int relation)
 184 {
 185         unsigned int newstate = 0;
 186
 187         if (cpufreq_frequency_table_target(policy, &elanfreq_table[0],
 188                                 target_freq, relation, &newstate))
 189                 return -EINVAL;
 190
 191         elanfreq_set_cpu_state(policy, newstate);
 192
 193         return 0;
 194 }
 195
 196
 197 /*
 198  *      Module init and exit code
 199  */
 200
 201 static int elanfreq_cpu_init(struct cpufreq_policy *policy)
 202 {
 203         struct cpuinfo_x86 *c = &cpu_data(0);
 204         unsigned int i;
 205         int result;
 206
 207         /* capability check */
 208         if ((c->x86_vendor != X86_VENDOR_AMD) ||
 209             (c->x86 != 4) || (c->x86_model != 10))
 210                 return -ENODEV;
 211
 212         /* max freq */
 213         if (!max_freq)
 214                 max_freq = elanfreq_get_cpu_frequency(0);
 215
 216         /* table init */
 217         for (i = 0; (elanfreq_table[i].frequency != CPUFREQ_TABLE_END); i++) {
 218                 if (elanfreq_table[i].frequency > max_freq)
 219                         elanfreq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
 220         }
 221
 222         /* cpuinfo and default policy values */
 223         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 224         policy->cur = elanfreq_get_cpu_frequency(0);
 225
 226         result = cpufreq_frequency_table_cpuinfo(policy, elanfreq_table);
 227         if (result)
 228                 return result;
 229
 230         cpufreq_frequency_table_get_attr(elanfreq_table, policy->cpu);
 231         return 0;
 232 }
 233
 234
 235 static int elanfreq_cpu_exit(struct cpufreq_policy *policy)
 236 {
 237         cpufreq_frequency_table_put_attr(policy->cpu);
 238         return 0;
 239 }
 240
 241
 242 #ifndef MODULE
 243 /**
 244  * elanfreq_setup - elanfreq command line parameter parsing
 245  *
 246  * elanfreq command line parameter.  Use:
 247  *  elanfreq=66000
 248  * to set the maximum CPU frequency to 66 MHz. Note that in
 249  * case you do not give this boot parameter, the maximum
 250  * frequency will fall back to _current_ CPU frequency which
 251  * might be lower. If you build this as a module, use the
 252  * max_freq module parameter instead.
 253  */
 254 static int __init elanfreq_setup(char *str)
 255 {
 256         max_freq = simple_strtoul(str, &str, 0);
 257         printk(KERN_WARNING "You're using the deprecated elanfreq command line option. Use elanfreq.max_freq instead, please!\n");
 258         return 1;
 259 }
 260 __setup("elanfreq=", elanfreq_setup);
 261 #endif
 262
 263
 264 static struct freq_attr *elanfreq_attr[] = {
 265         &cpufreq_freq_attr_scaling_available_freqs,
 266         NULL,
 267 };
 268
 269
 270 static struct cpufreq_driver elanfreq_driver = {
 271         .get            = elanfreq_get_cpu_frequency,
 272         .verify         = elanfreq_verify,
 273         .target         = elanfreq_target,
 274         .init           = elanfreq_cpu_init,
 275         .exit           = elanfreq_cpu_exit,
 276         .name           = "elanfreq",
 277         .attr           = elanfreq_attr,
 278 };
 279
 280 static const struct x86_cpu_id elan_id[] = {
 281         { X86_VENDOR_AMD, 4, 10, },
 282         {}
 283 };
 284 MODULE_DEVICE_TABLE(x86cpu, elan_id);
 285
 286 static int __init elanfreq_init(void)
 287 {
 288         if (!x86_match_cpu(elan_id))
 289                 return -ENODEV;
 290         return cpufreq_register_driver(&elanfreq_driver);
 291 }
 292
 293
 294 static void __exit elanfreq_exit(void)
 295 {
 296         cpufreq_unregister_driver(&elanfreq_driver);
 297 }
 298
 299
 300 module_param(max_freq, int, 0444);
 301
 302 MODULE_LICENSE("GPL");
 303 MODULE_AUTHOR("Robert Schwebel <r.schwebel@pengutronix.de>, "
 304                 "Sven Geggus <sven@geggus.net>");
 305 MODULE_DESCRIPTION("cpufreq driver for AMD's Elan CPUs");
 306
 307 module_init(elanfreq_init);
 308 module_exit(elanfreq_exit);